1. Technical Field
The present invention relates to a technology that controls light-emitting elements such as organic light emitting diode (OLED) elements.
2. Related Art
A light-emitting device having a plurality of light-emitting elements has been proposed. In the light-emitting device, a deviation in luminance of the light-emitting element occurs due to various reasons such as the delay of a signal representing luminance of a light-emitting element (hereinafter referred to as a (“data signal”).
For example, a light-emitting device having a construction in which a plurality of pixel circuits, each having a light-emitting element, is connected to a common line (hereinafter referred to as a “data signal line”) has been proposed. In this construction, the data signal which specifies luminance of each light-emitting element in a time sharing manner is sequentially input from the data signal line to each pixel circuit for a predetermined period (hereinafter referred to as a “sampling period”) and a driving signal generated on the basis of the data signal luminance of a light-emitting element is supplied to control the luminance of the light-emitting element. In this construction, if a period when the data signal is maintained at a level corresponding to the luminance of one light-emitting element and a sampling period for the data signal completely coincide with each other on a time axis, the luminance of the light-emitting element can be properly controlled by supplying a predetermined period of the data signal to each pixel circuit. However, there is a case where a data signal is delayed for the sampling period due to various reasons, such as an unsharpened waveform when the signal is propagated along the data signal line. In this case, since a level of the data signal is varied within one sampling period, a predetermined driving signal cannot be supplied to a light-emitting element. As a result, a deviation in luminance of the light-emitting element may occur.
As technologies for solving the above problem, JP-A-5-241536 (FIGS. 1 and 2) or JP-A-9-212133 (FIGS. 1 and 2) discloses a construction in which an interval Pd is inserted between sampling periods Ps, as shown in FIG. 16. Corresponding to the above construction, during the interval Pd from the end point of each sampling period Ps to the start point of the sampling period Ps immediately after thereof, a data signal D is not supplied to any pixel circuit. Therefore, even though the data signal D is delayed by a time length Δd as indicated by “D (delayed)” in FIG. 16, deviation is not generated in luminance of a light-emitting element if the delay amount Δd falls within a range of a time length of the interval Pd.
In the related art, however, a time length (the sampling period Ps) in which the data signal D is supplied to each pixel circuit must be shortened as long as the interval Pd. Therefore, when a data signal must be sampled within a short period in each pixel circuit (e.g., when the number of pixel circuits connected to the data signal line is many), a problem arises because the data signal cannot be sufficiently supplied to each pixel circuit and it becomes difficult to control the luminance of each light-emitting element.